The present invention relates to a sanitary napkin comprising a three dimensionally-shaped tube of absorbent material and a method of making the same. A method of individually packaging a three dimensionally-shaped absorbent article is also described.
Absorbent articles such as sanitary napkins, pantiliners, disposable diapers, incontinence products, and bandages are designed to absorb and retain liquid and other discharges from the human body and to prevent body and clothing soiling.
A need that occurs. in the manufacture of absorbent articles is to provide the absorbent article with more complex three dimensional shapes in an effort to more closely fit the wearer""s body. In the past, a number of efforts were made to create body-conforming articles.
One way to provide an absorbent article with a body-conforming shape, for instance a triangular cross-section for a sanitary napkin, was often to stack elements on top of one another. Examples of such structures are shown in U.S. Pat. No. 4,340,058 issued to Pierce, et al. on Jul. 20, 1982, and U.S. Pat. No. 4,490,147 issued to Pierce, et al. on Dec. 25, 1984. Stacking materials to form three dimensionally-shaped absorbent articles suffers from the drawback that it is very difficult to carry out on high. speed manufacturing processes. This is due to difficulties encountered with registration and differences in extensibility of the materials (which are usually supplied in continuous form) that are stacked. That is, it is difficult to maintain such materials in the precise degree of alignment with respect to each other that is necessary for stacking. If continuous webs have different cross-sectional areas, the webs with the smaller cross-sectional area will tend to stretch more in such a process under the same amount of force than will webs having a larger cross-sectional area.
Other efforts involved molding the absorbent article, or an element thereof into a body-conforming shape. One such effort is described in U.S. Pat. No. 5,197,959 entitled xe2x80x9cAbsorbent Articlexe2x80x9d issued to Buell on Mar. 30, 1993. The search for improved body-conforming absorbent articles, and methods for making the same, has continued.
Thus, a need exists for absorbent articles with complex, body-fitting shapes that do not involve stacking elements of various shapes different from the shape desired, or molding an element, in order to form an absorbent article of the desired shape.
The present invention is directed to an absorbent article comprising a three dimensionally-shaped tube of absorbent material and a method of making the same.
In one preferred embodiment, the absorbent article is a compound sanitary napkin. The compound sanitary napkin comprises a base pad having a body-facing side, a garment-facing side, and a longitudinal centerline. The base pad preferably comprises a liquid pervious topsheet, a liquid impervious backsheet joined to the topsheet, and an absorbent core positioned between the topsheet and the backsheet. A tube of absorbent material is positioned on the body-facing side of the base pad and is aligned along the longitudinal centerline of the base pad.
The tube of absorbent material preferably comprises an absorbent material and a cover at least partially wrapping the absorbent material. The absorbent material is preferably penetrated by autogenous bonds that join one portion of the cover to an opposing portion of the cover to provide the tube with a unique three dimensional shape. In a particularly preferred embodiment, the tube of absorbent material has a tri-lobal cross-sectional configuration, at least in the center of the sanitary napkin. The tri-lobal cross-sectional configuration comprises an inverted xe2x80x9cTxe2x80x9d-shaped cross-section comprising an upright central lobe symmetrically disposed about the longitudinal centerline and two outer lobes. The central lobe has a greater caliper than the two outer lobes, and is preferably capable of fitting comfortably in the space between the wearer""s labia majora and minora.
The present invention is also directed to a method of making a shaped tube of absorbent material for the sanitary napkin described above. The method preferably comprises the steps of:
(a) providing a web of absorbent material, the web of absorbent material having a length, a width, a longitudinal centerline oriented in the direction of the length of the web of absorbent material, a first surface and an opposed second surface;
(b) providing a cover for the first and second surfaces of the web of absorbent material;
(c) at least partially covering the first and second surfaces of the web of absorbent material with the cover to form a composite web having longitudinal side margins;
(d) folding the composite web at least once with folds defining fold lines that are arranged about the longitudinal centerline of the web of absorbent material; and
(e) autogenously bonding a portion of the cover that covers the first surface of the web of absorbent material to a portion of the cover that covers an opposing portion of the second surface of the web of absorbent material.
In particularly preferred versions of the method of the present invention, the web of absorbent material comprises an absorbent foam material. The absorbent foam material preferably comprises a high internal phase emulsion (or xe2x80x9cHIPExe2x80x9d) foam. The web of absorbent foam material is preferably formed into a plurality of particles of foam. In a preferred embodiment, this occurs between the step (c) of at least partially covering the first and second surfaces of the web of absorbent material with the cover to form a composite web, and the step (d) of folding the composite web at least once.
The step (d) of folding the composite web at least once may further comprise: (i) folding the longitudinal side margins of the composite web inward toward the longitudinal centerline about a first set of longitudinally-oriented folding lines to form a C-folded structure; and then (ii) folding the composite web inward about the longitudinal centerline so that the longitudinal side margins of the folded composite web are brought adjacent to each other.
The bonded and shaped tube of absorbent material is joined to a base pad to form a compound sanitary napkin. In some embodiments, the ends of the tube of absorbent material are splayed out before the tube of absorbent material is attached to the base pad to provide the tube with a more pronounced profiled shape.
Numerous alternative embodiments and features for the absorbent article are included within the scope of the present invention. A method of individually packaging a three dimensionally-shaped absorbent article is also described.